While the Accessport can do much more, realizing that it logs hundreds of data points from the vehicle to CSV format was definitely a highlight, seeing as Splunk can easily index CSV data. If you’re familiar with Splunk you know there is only one thing to do here: Splunk #allthethings! I wasn’t sure if these performance parts would really make my car perform that much better, and I didn’t know would kind of adverse effects there would be after me pulling pieces out of my engine and replacing them with aftermarket parts. I figured the best way to get to the bottom of this would be to stick to the facts and analyze the data using an awesome data analytics engine – Splunk.
Tuning my ride
To lay down some background information, I drive a 2015 Subaru WRX. Stock, it pushes 268 HP at 5600 RPM and 258 lb.-ft of torque from 2000-5200 RPM. If that doesn’t make sense to you, don’t worry. All you need to know is roughly the higher the numbers, the more power you’re going to get out of your car. The WRX comes stock with a turbo charger so that helps boost your power significantly more than a basic flat-four engine. I knew I wanted to make some specific upgrades to my car that dealt with both aesthetics (well, how my car sounded) and performance. I chose to make a few upgrades here:
- Cobb Big SF cold air intake
- Cobb Accessport Stage 1 Engine Control Unit (ECU) tune / Cobb Accessport Stage 1+ ECU tune
- Nameless 4” axelback exhaust
How I got my data
The Accessport logs data directly to a CSV file on the device itself. Using a micro usb to USB adapter, I was able to extract the CSV files using Cobb’s free Access Manager software. To avoid blinding myself with spreadsheets of thousands of numbers, I uploaded my data directly to Splunk with a monitoring statement. For more info on how to set that up, take a look at Splunk’s inputs.conf documentation.
Nothing too fancy was done to obtain this data (but I am working on running a Raspberry Pi from my center console to hopefully bring data in remotely from anywhere on the road – stay tuned for that!). Copying the data from the device to my Macbook sufficed here with a monitor statement. For demo purposes, I’ve left the sourcetype name as the pre-defined “csv” sourcetype and gave it an index.
Naturally, recording the data here was the most fun of all. Having a newborn son, it’s a little hard to get out of the house whenever I choose, so I spent my December mornings at 5AM logging 2nd gear pulls on the interstate on-ramp by my house. Like I said – the most fun of all.
Hearing what my car had to say
Enough of a description, let’s show you what my WRX data had to say. I made a few runs (datalogs) with a few different tunes set on my car. The standardized test I used is as follows:
- On a straight road, cruise at 2500 RPM in second gear.
- Enable data logging
- Open the throttle as fast as my foot can hit the floor until I redline (6700 RPM)
- Let off the throttle and disable data logging
I ran the same test in three different scenarios:
- Stock engine
- Stage 1 tune (a software update for the ECU)
- Stage 1+ tune (Stage 1 tune plus adjustments for the Cobb Big SF cold air intake
One of the most well-known measurements we will look at, yet usually misunderstood, is boost. Boost is measured as the difference between your engine’s air pressure and barometric pressure, measured in pounds per square inch (PSI) (engine air pressure absolute – barometric pressure absolute = boost level in PSI). For all readers that don’t live a double life as a meteorologist, barometric pressure is the pressure of the air outside of your car . At a very high level, the goal of a turbocharger is to boost the amount of air intake into the engine to allow the mixing of more fuel and air to increase combustion energy and *poof* you have more power thanks to forced induction. That said, more boost doesn’t always mean more power; there is a method to the madness. Running my engine stock showed a steady increase of boost as my RPMs increased thanks to my foot being glued to the floor. Stock was cool, but we want more power and we want it now! Running my car’s ECU at a Stage 1 tune allowed for that “boost” of boost we were looking for. The yellow line on the graph below shows what a simple Stage 1 adjustment can do. Relative to Stock, it felt like I was glued to the back of my bucket seat as it really woke up my car.